Network performance loss on AMD system after upgrading to SLES9 SP4

  • 3408793
  • 26-Mar-2008
  • 27-Apr-2012


Novell SUSE Linux Enterprise Server 9 Service Pack 4 (SLES9 SP4)
Novell Open Enterprise Server 1 (OES 1) Support Pack 2 Linux
Novell Linux Desktop 9

AMD CPUs (Rev. F and newer)


After upgrading the system to a SLES9 SP4 (or equivalent) kernel, the network transfer performance (e.g copying files via scp) drops dramatically.



This issue
can be worked around by updating to the current maintenance kernel for SP4 and booting it with the kernel parameter

Status (Last updated: 2008-12-10)

A fix for this issue which does away with the need for the additional kernel parameter is expected to be included in the next maintenance update of the kernel for the affected products.


Reported to Engineering

Additional Information

Root cause

C1E, "Enhanced CPU State 1", is a power save state implemented in modern AMD CPUs (RevF and newer). This feature and these processors were not available when CODE9 products like SLES9 were originally released. When this state is enabled, some systems do not boot or have timer issues. This has been fixed in the SLE10 products. For the older kernel used in the CODE9 products, the proper fix was too intrusive to backport and an alternative approach has been taken: to add code to prevent C1E from being entered on systems where C1E triggers problems. Unfortunately, some of these systems are not yet detected properly. The workaround forces disabling of C1E regardless.

Change Log

03 Mar 2009 - Cheryl King - Changed all instances of "Support Pack" to Service Pack (for SUSE Linux)
2008-12-10 - Ray Dassen - Update to reflect that a proper fix is expected in the next maintenance update of the kernel.
2008-11-25 - Ray Dassen - Reworked: we have confirmation that the issue is not fixed yet.